Process and apparatus for operating a primary furnace



F. K. VIAL PROCESS AND APPARATUS FOR OPERQTING A PRIMARY FURfI ACE July25, 1939.

Filed Dec. -2, 1937 2 Sheets-Sheet 1 F. K. VIAL July 25, 1939.

PROCESS AND APPARATUS FOR OPERATING A PRIMARY FURNACE Filed Dec. 2,19257 2 Sheets-Sheet 2 20 through, thus permitting the maximum amountPatented Jul 25, 1939 h I 4 2,167,596

UNITED. STATES PATENT OFFICE PaocEssfANn APPARATUS FOR orEaAmG- AranuARY FUaN cE A Frederick K. Vial, Chicago, 111., assignor to Grif-'fln Wheel- Company, Chicago, 111., a, corporation of MassachusettsApplication December 2, 1931, Serial No. 171,115 '1 Claims. (c1. ass-14)My invention relates to metal working appafer system since the purposeof the system is to ratus and the process of operating said apparatustransfer a maximum amount of the heat from and more'particularly' tosuch an apparatus as exhaust gases into the incoming air of combusthatgenerally described in my Patent No. tion, and the latter in that thecost of heat- 5 2,078,747, issued April 27, 1937. I resisting alloys isso great as to make such an 5 My invention is'directed to an improvementin" arrangement a commercial impracticability. the general type of metalmelting equipment de- Accordingly, I have devised a system of heatscribed in the said Patent No. 2,078.747 wherein transfer for suchequipment which will permit a pre-heater is used in combination with ameltcontinued use of the present materials, will maining cupola. I tainsubstantially the present heat transfer efii- 10 An object of myinvention is to improve the ciency, and will permit a cost not to exceedthat manner of utilizing the waste gases from the at present incurred.

cupola asa means of pre-heating the cold air A more specific object ofmy invention is to of combustion which is normally drawn from theprovide an eflicient means of heat transfer beatmosphere. I X v Q tweenincoming air of combustion and outgoing l5 It is known in the art thatthe most eificient hot gases in such a structpre as that described formof heat transfer between gases takes place which will at the same timepermit use of cold when these gases traverse adjacent conducting air tomoderate temperatures developed in critimedium, passing in oppositedirections therecal areas of the pre-heater and combustion chamr. ofconduction to take place between the two me- Another object of myinvention is to provide diums as they travel through their respectiveconsuch an arrangement of ducts for the cold air duits. Such anarrangement is shown in my of combustion and the hot exhaust gases insuch above-mentioned Patent, w erei a structure as I have hereindescribed as will the exhaust gases from a cupola are passed permit theuse of any portion or all of said cold 5 through a series of pipes in apre-heater while air of combustion to modify the high tempera- I, thecold air is circulated around said pipes by tures developed in criticalareas thereof. a baflle construction within said heater in a Otherobjects, features and advantages are direction substantially opposite tothat taken by comprehended by my invention as will appear in the exhaustgases. the further description and drawings formin ,8: 30

In operation certain dimculties have been enpart of this specification.countered in such a construction due to the fact In the drawingsFlgure 1is a view in elevation that the incoming cold gases-reach a maximum of acupola and pre-heater structure embodying temperature in the same areaof the heater where my invention, a portion of said pIe heater being theoutgoing exhaust gasesfrom the cupola and shown in section; 35

' the combustion chamber are also hottest. Due Figure 2 is a plan viewof the structure shown to this fact the constructionof the heater at thein Figure 1; and said area issubject-to rapid deterioration with Figure3 is a side elevation of the cupola and the result that it is impossibleto maintain such 1 pre-heater structure shown in Figures 1 and 2. 40. astructure in operative condition except for a Describing this embodimentof myinvention 4o relatively short period. Means of overcoming indetail, it comprises the primary furnaces herethis difllculty have beensuggested such as therin shown as re-melting cupolas 2 and 4 of themostatically controlling the exhaust gases to such usual form supportedon the base structures 6 a temperature that the sheet and tubeconstrucand 8. Near the base the cupolas have bustle tion in the areaunder consideration will last a pipes I0 and I2 with the tuyere leadsl4, l4 and 45 suflicient lengthof time to make the construction tuyereboxes l6, l6, comprising means for cona commercial one. Anothersuggested remedy is ducting the gas-to the usual tuyeres. Gases are sucha construction of the pre-heater plates and conducted into the bustlepipes ill and I2 through pipes in the said area as will provideresistance the hot blast pipe [8 which forms a juncture with to theexcessive temperatures which occur therethe respective bustle pipesthrough the gates at 50 at and it is known that such construction can 20and 22. At a height slightly below the chargbe provided by the use ofcertain heat-resisting "mg door 24 the respective cupolas are surroundedalloy metals. Both of the above-mentioned remby the circular ducts 26and 28 through which: 1 ediesare open "to objections; the former in thatpartially burned gases may be drawn off from it zreitwmeznmes r e peatiransthe cupolas. The circular ducts 2s and 20 have u the clean-outdoors 30, 3'3 and gas outlets leading respectively into the vertical gasducts 32 and 34 having the clean-out doors 33, 33, both of said ductsdischarging into the auxiliary combustion chamber 36. Air for thecombustion chamber 35 is withdrawn from the cold blast pipe 60 at thegate 31 and delivered through the ducts 4i and 43 into the larger ducts32 and 34, respectively, as at 45 and 41 (Figure 2). From the combustionchamber 36 the hot gases pass into the distributing chamber 38 and fromthe distributing chamber into the body portion 39 of the pre-heater in adownward direction through the multiplicity of fiues or conduits 40, 40into the transfer chamber 42 and thence through the duct 44",ilil20 thetransfer chamber 46 from which they pass in an upward direction throughthe flues 40, 4D in the body portion 48 of the pre-heater and thus intothe exhaust chamber 50. The hot gases are discharged from the exhaustchamber 50 through the exhaust pipe 52 by means of the exhauster 54 intothe exhaust stack 56, whence they are discharged into the open air.Support for the pre-heater and for the combustion chamber is provided bythe platform indicated at 35 and for the exhauster and the exhaust stackby the platform indicated at 53. The exhaust chamber 50 as well asgthedistributing chamber 38 and the transfer chambers 42 and 46 have theusual clean-out doors 49, 49.

The cold air of combustion is drawn in from the atmosphere by means ofthe blower indicated diagrammatically at 58 (Figure 1) and is forcedthrough the cold blast pipe 60 and the gate 6| into the upper part ofthe pre-heater body 39 as at 62, saidupper part of this portion of thepreheater being separated from the remainder thereof by the horizontalpartition plate 63 which is perforated to accommodate the verticallyarranged flues 40, 40. The partition plate 63 thus 4 divides the bodyportion 39 of the pro-heater into upper and lower compartments and theincoming air from the cold blast pipe 60 is discharged through the saidupper compartment into the duct 84, whence it passes into the upper endof the pre-heater body 48 as at 66. From the upper area. of thepre-heater body "the cold blast is directed alternately back and forthin horizontal directions by the baffle plates 61, .61 and around thefines 40, 40 into the lower area thereof, whence it is dischargedthrough the horizontal duct 10 into the lower area of the pre-heaterbody 39 through which it is directed back and forth in horizontal directons by the baflle plates 61, 81 and thence thro h the opening I4 intothe hot .blast pipe II. The path 'oi' this cold blast from the gate 6|through the two portions of the pre-heat'er is shown by the continuousarrow indicated at various points as l2, l2.

It will thus be seen that by separating a relatively small upper portionof the pre-heater body 39 from theremainder thereof by the partitionplate 63 and conducting therethrough the cold blast or a part thereof, Ihave provided a means of protection for the pipes or flues 40, 40 andfor the structural plates of the distributing chamber and of the heaterbody in the vicinity where the hottest gases enter the pre-heater fromthe combustion chamber 36. By this modification I have provided at thiscritical juncture of the structure a means of controlling thetemperature of said flues and plates and preventing their rapiddestruction or disintegration by the excessive temperature otherwiseprevailing. It willalso be observed that I have faciliated thisarrangement by constructing the pre-heater in two portions so arrangedwith respect to each other that the hot gases pass in a verticallydownward direction through one portion and in a vertically upward 5direction through the other portion, whereby I may efllciently provideentrance for the cold blast at one end of the pre heater as at 66 and anexhaust at the other end of the pro-heater as at 14 while at the sametime utilizing the cold blast as a means of moderating the temperaturesto which the iiues and plates are subjected in that area of thepre-heater where the hot gases enter it. By this construction I have anarrangement wherein the direction of flow of the. 15 cold blast throughthe pre-heater is counterwise to the direction of flow of the hot blastthrough substantially the entire length of the pre-heater, thus securingthe most eflicient heat transfer therebetween while at the same time Ihave uti- 20 lized the cold blast as a means of moderating the hightemperatures of the before-mentioned fiues and plates in the mostcritical area of the preheater construction as above described.

It may be further noted that the cold blast duct 60 is divided as at 16'(Figure 2) into two legs, one of which leads to the gate 6! as alreadydescribed and the other of which is in the form of a by-pass I8 aroundthe pre-heater body 39 to the gate whence cold air may be discharged 30directly into the upper part of the body portion 48 of the pre-heater asat 82. By thus dividing the cold blast I may at will modify theproportion which is carried through the by-pass I8 directly into theupper area of the pre-heater body 48 as .35 compared with the proportionof the cold blast which isfirst led through the upper portion of thepre-heater body 39 as a means of modifying the temperatures thereinbefore being led through the duct 64 into the said upper area of thepreheater body 48.

By this compact arrangement of parts and particularly the division ofthe pre-heater into two vertical sections side by side, with a commoncombustion chamber serving both, and the dual cupolas operated-inconjunction therewith, I have devised a most emcient arrangement bywhich adequate protection is afforded that portion of the pre-heaterwhich has heretofore been most susceptible to quick deterioration. Myexrience has indicated that with structures of his specific type it isdesirable to have by far the greater portion or all of the cold blastdirected through the independent chamber at the top of the pre-heaterbody 38, thus using it as a cooling medium for the critically hightemperatures developed in that area. Nevertheless, it will be apparentto those skilled in the art that under certain conditions it may. bedesirable to by-pass a portion of said cold air blast around so thepre-heater body 39 directly into the upper portion of the pre-heaterbody 43. By the arrangement I have devised, the most eflicie t divisionof this cold blast is readily provided or by control of the gates at Eland 80 respectively. 65

be limited by the exact embodiment of the device shown, which is merelyby way of ilustration and not limitation, as various andother forms ofthe device will of course be apparent to those skilled in the artwithout departing from the spirit of the invention or the scope of theclaims.

I claim:

1. In a heat exchanger, a pre-heater having adjacent hot and coldends'and interlaced passageways therebetween for conducting hot and coldgasesrespectively, said cold gas passageway comprising an entrance tothe cold end of said p e-heater through an independent passageway at thehot end thereof, and an exit adjacent said entrance at said hot end.

2. In a combustion system a primary combustion furnace, an auxiliarycombustion chamber, a pre-heater having a narrow zone at the hot enddivided from the main body thereof, means for conducting atmospheric airthrough said zone directly to the opposite end of said pre-heater and ina. given direction therethrough and thence into said primary combustionfurnace as a means of combustion therefor, and means for withdrawingpartially burned gases from said primary furnace and conducting them tosaid auxiliary chamber and for conducting the gases from said chamberthrough the length of said pre-heater in a direction reverse to thatfirst mentioned, said pre-heater being so constructed and arranged as topermit the hot and cold ends to be adjacent.

3. In a heat transfer system, a pre-heater having adjacent hot and coldends, an independent zone at the hot end thereof, means for conducting acold blast through said zone directly to the cold end of said pre-heaterand in a given direction through substanaially the length of saidpre-heater, and means for conducting hot gases through the length ofsaid pre-heater in a direction reverse to that first mentioned, wherebyprotection is afforded the structure at the hot end of said pre-heaterwhile maintaining the most eflicient means of heat transfer between saidcold blast and hot gases.

4. In a combustion system a pre-heater having adjacent hot and coldends,an independent zone at one end and means for conducting air through saidzone directly to the cold end of said preheater and through saidpre-he'ater in a given direction, and nieans for conducting hot gasesthrough the length of said pre-heater in a direction reverse to thatfirst mentioned, whereby said air and said hot gases traverse saidpre-heater in reverse directions for substantially the length thereofand afiord maximum efficiency of heat transfer therebetween while at thesame time said air serves to moderate the maximum temperatures at thehot end of said pre-heater.

5. The method of heating a gas by passing a hot gas and the gas to beheated over opposite sides of a heat transfer means in the form of apro-heater comprising passing the gas to be heated through that portionof the pre-heater where the hot gas enters directly into the adjacentportion of the pre-heater where the hot gas is discharged and thereafterpassing it in contact with intermediate portions of said preheaterthrough substantially the length thereof in a direction reverse to thattraversed by hot gas.

6. A heat exchanger in the form of a pre-heater having adjacent hot andcoldends, means for passing the hot gases through said pre-heater in agiven direction, means conducting atmospheric air through saidpre-heater adjacent the hot end thereof directly into the cold end, andmeans for conducting said air through substantially the length of saidpre-heater in a direction reverse to that traversed by said hot gases,whereby said air serves to moderate the temperatures at the hot end ofsaid pre-heater while said parts are so constructed and arranged as topermit eflicient heat transfer between said air and said gases forsubstantially the length of said pre-heater.

'7. In a heat exchanger, a pre-heater having adjacent hot and cold endsand interlaced passageways therebetween for conducting hot and coldgases respectively, said cold gas passageway comprising an entrancethrough the hot end of said pre -heater to the cold end thereof, and anexit adjacent said entrance at said hot end.

FREDERICK K. VIAL.

